Automotive driveline systems include complex gear trains and turbomachinery that rely on petroleum products to provide a hydraulic working fluid and lubricant. Specifically, passenger car automatic transmissions and transaxles use turbines, pumps, gears and clutches operating at high speed and high temperature in a lubricant. The high speed rotation and high power densities of these systems, combined with the air space in the system and air entrained in the lubricant, may result in the formation of foam. Foam, consisting of a small quantity of lubricant and a large quantity of air, compromises pump efficiencies by changing the compressibility of the lubricant. As a result, pistons and valves actuated by the lubricant may not function correctly if the air content of the working fluid is large. Furthermore, the gear trains may receive inadequate lubrication, due to low pump efficiencies and a reduced capacity for the lubricant to provide a cooling effect, if a foam condition exists. Modern designs of drivetrain hardware are trending towards small sumps and higher power throughput densities, and relying upon less lubricant in general than prior designs. A lower lubricant volume may compound the challenge of dispelling foam from drivetrain system under operating conditions over a period of time. These foaming issues are exacerbated when the lubricant has a low viscosity because the typical chemistry used as antifoam additives is unable to stay suspended making “drop out” a concern. Because driveline system lubricants are moving to lower and lower viscosities to try and make gains in fuel economy the problems associated with foaming have increased.
The present invention addresses the problems of foaming in low viscosity lubricants by introducing unique antifoam chemistry that is capable of remaining suspended in lubricant formulations even when the lubricant has kinematic viscosities as low as 2-8 cSt or even 2-5 cSt at 100° C.
In one embodiment, the invention relates to a lubricant composition comprising a base oil having a kinematic viscosity between 2 and 8 cSt at 100° C., or alternatively between 2 and 6 cSt at 100° C., or in a further alternative between 2 and 5 or between 2 and 4.5 cSt at 100° C.; and an additive composition represented by formula I:
wherein x and y can be the same or different and (x+y) equals between 50 and 1,500 and R is a polyoxyalkylene group. Generally, according to the present invention, the base oil is present in a major amount whereas the additive composition of the invention is present in a minor amount. It is to be understood that according to the invention, a “major amount” is greater than “a minor amount”. In a particular embodiment, a “major amount” relates to at least 50 weight-% of the composition. In an alternative embodiment, the term “a major amount” relates to at least 70, or at least 80, or at least 90 or even at least 98 weight-% of the composition. In one embodiment, R has a molecular weight of 500-5000 g/mol.
In one embodiment, said minor amount of an additive composition delivers between 2 and 500 ppm of silicon to the lubricant composition.
In another embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein x is between 100 and 300 and y is between 10 and 20.
In yet another embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein x is between 160 and 190 and y is between 14 and 18.
In yet another embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein R is represented by formula II:—(CH2)a—O—(R1)b-Q  IIand R1 is a combination of ethylene oxide and propylene oxide units, Q is hydrogen or a monovalent organic group selected from the group consisting of C1-C8 alkyl, acetyl and isocyanato group of the formula —NCO, subscript a is a positive integer of 2-6 and subscript b is a positive integer of 5-100.
In still another embodiment a lubricant composition may comprise an additive composition represented by formula 1 wherein R is represented by formula II and wherein subscript a is a positive integer of 2-6 and subscript b is a positive integer of 20-70.
In still another embodiment a lubricant composition may comprise an additive composition represented by formula I wherein R is represented by formula II and wherein subscript a is a positive integer of 2-6 and subscript b is a positive integer of 25-45.
In one embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein R is represented by formula II and wherein R1 is represented by formulas III:(C2H4O)m(C3H6O)n or (C3H6O)n(C2H4O)m  IIIand wherein m is a positive integer of 1-10 and n is a positive integer of 5-50.
In another embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein R is represented by formula II and wherein R1 is represented by formulas III and wherein m is a positive integer of 3-6 and n is a positive integer of 20-40.
In still another embodiment, a lubricant composition may comprise an additive composition represented by formula I wherein R is represented by formula II and wherein R1 is represented by formulas III and formula III is a polymer selected from the group consisting of a random copolymer or a block copolymer.
In another embodiment, a lubricant composition may comprise a base oil having a kinematic viscosity between 2 and 8 cSt at 100° C., or in another embodiment between 2 and 6 cSt at 100° C., or in yet another embodiment between 2 and 5 or between 2 and 4.5 cSt at 100° C., and an additive composition represented by formula IV:
wherein x and y can be the same or different and (x+y) equals between 50 and 1,500 and m and n can be the same or different and Q is hydrogen or a monovalent organic group selected from the group consisting of C1-C8 alkyl, acetyl and isocyanato group of the formula —NCO. As stated above, generally, according to the present invention, the base oil is present in a major amount whereas the additive composition of the invention is present in a minor amount. It is to be understood that according to the invention, a “major amount” is greater than “a minor amount”. In a particular embodiment, a “major amount” relates to at least 50 weight-% of the composition. In an alternative embodiment, the term “a major amount” relates to at least 70, or at least 80, or at least 90, or at least 98 weight-% of the composition.
In another embodiment a lubricant composition may comprise an additive composition represented by formula IV wherein x is between 160 and 190 and y is between 14 and 18, m is a positive integer of 3-6 and n is a positive integer of 20-40, and Q is hydrogen or methyl.
In another embodiment a lubricant composition may comprise an additive composition represented by formula I wherein said additive composition delivers between 2 and 50 ppm of silicon to the lubricant composition.
In another embodiment a lubricant composition may comprise an additive composition represented by formula I wherein said additive composition delivers between 2 and 25 ppm of silicon to the lubricant composition.
In another embodiment a lubricant composition of the invention may comprise a base oil having a kinematic viscosity between 2 and 6 cSt at 100° C., or alternatively between 2 and 4.5 cSt at 100° C.
In yet another embodiment a lubricant composition of the invention may further comprise an oil-soluble ashless dispersant selected from the group consisting of: a succinimide dispersant, a succinic ester dispersant, a succininic ester-amide dispersant, a Mannich base dispersant, phosphorylated, boronated or phosphorylated and boronated forms thereof.
In yet another embodiment of the invention, a lubricant composition may further comprise one or more of the following: an air expulsion additive, an antioxidant, a corrosion inhibitor, a foam inhibitor, a metallic detergent, an organic phosphorus compound, a seal-swell agent, a viscosity index improver, and an extreme pressure additive.
In still another embodiment the invention includes a method of lubricating a machine part comprising lubricating the machine part with a lubricant composition comprising a minor amount of an additive composition of the invention.
In another embodiment, the invention includes a method wherein the minor amount of an additive composition delivers between 2 and 500 ppm of silicon to the lubricant composition.
In another embodiment, the invention includes a method wherein the machine part comprises a gear, an axle, a differential, an engine, a crankshaft, a transmission, or a clutch.
In another embodiment, the invention includes a method wherein the transmission is selected from the group consisting of an automatic transmission, a manual transmission, an automated manual transmission, a semi-automatic transmission, a dual clutch transmission, a continuously variable transmission, and a toroidal transmission.
In another embodiment, the invention includes a method wherein the clutch comprises a continuously slipping torque converter clutch, a slipping torque converter clutch, a lock-up torque converter clutch, a starting clutch, one or more shifting clutches, or an electronically controlled converter clutch.
In another embodiment, the invention includes a method wherein the gear is selected from the group consisting of an automotive gear, a stationary gearbox, and an axle.
In another embodiment, the invention includes a method wherein the gear is selected from the group consisting of a hypoid gear, a spur gear, a helical gear, a bevel gear, a worm gear, a rack and pinion gear, a planetary gear set, and an involute gear.
In another embodiment, the invention includes a method wherein the differential is selected from the group consisting of a straight differential, a turning differential, a limited slip differential, a clutch-type limited slip differential, and a locking differential.
In another embodiment, the invention includes a method wherein the engine is selected from the group consisting of an internal combustion engine, a rotary engine, a gas turbine engine, a four-stroke engine, and a two-stroke engine.
In another embodiment, the invention includes a method wherein the engine comprises a piston, a bearing, a crankshaft, and/or a camshaft.
In another embodiment, the invention includes a method for improving the antifoam properties of a lubricating fluid comprising an additive composition of the invention. In particular, the additive composition of the invention can be used to improve the antifoam properties of a lubricating fluid having a kinematic viscosity of between 2-8 cSt at 100 C, or alternatively between 2 and 6 cSt at 100° C., or in a further alternative between 2 and 5 or 2 and 4.5 cSt at 100° C.
In one embodiment the invention therefore includes a method for improving the antifoam properties of a lubricating fluid having a kinematic viscosity of between 2-8 cSt at 100 C, or alternatively between 2 and 6 cSt at 100° C., or in a further alternative between 2 and 5 or 2 and 4.5 cSt at 100° C., comprising including in a lubricating fluid an effective amount of one or more compounds of formula I
wherein x and y can be the same or different and (x+y) equals between 50 and 1,500 and R is a polyoxyalkylene group. In one embodiment, R has a molecular weight of 500-5000 g/mol.
In another embodiment the invention includes a method for improving the antifoam properties of a lubricating fluid having a kinematic viscosity of between 2-8 cSt at 100 C, or alternatively between 2 and 6 cSt at 100° C., or in a further alternative between 2 and 5 or 2 and 4.5 cSt at 100° C., comprising including in a lubricating fluid an effective amount of one or more compounds of formula IV
wherein x and y can be the same or different and (x+y) equals between 50 and 1,500 and m and n can be the same or different and Q is hydrogen or a monovalent organic group selected from the group consisting of C1-C8 alkyl, acetyl and isocyanato group of the formula —NCO.
In one embodiment, an effective amount of one or more compounds of formula I or IV delivers between 2 and 500 ppm of silicon to the lubricant composition. In alternative embodiments, an effective amount of one or more compounds of formula I or IV delivers between 2 and 50 ppm or between 2 and 25 ppm of silicon to the lubricant composition.
In another embodiment the invention includes a method for improving the antifoam properties of a lubricating fluid having a kinematic viscosity of between 2-8 cSt at 100° C., comprising including in a lubricating fluid an effective amount of one or more compounds of formula IV wherein x is between 160 and 190 and y is between 14 and 18 and m is a positive integer of 3-6 and n is a positive integer of 20-40, and Q is hydrogen or methyl.
In still another embodiment the invention includes a method for improving the antifoam properties of a lubricating fluid while lubricating an automotive component requiring lubrication, comprising adding a lubricating fluid to an automotive component requiring lubrication, the fluid comprising a base oil having a kinematic viscosity at between 2 and 5 cSt at 100° C., and one or more compounds of formula IV
wherein x and y can be the same or different and (x+y) equals between 50 and 1,500 and m and n can be the same or different and Q is hydrogen or a monovalent organic group selected from the group consisting of C1-C8 alkyl, acetyl and isocyanato group of the formula —NCO and operating the automotive component that contains the fluid, wherein the antifoam performance of the fluid is improved relative to the performance of a lubricating fluid free of the compound of formula IV.
In still another embodiment the invention includes a method for improving the antifoam properties of a lubricating fluid while lubricating an automotive component requiring lubrication, comprising adding a lubricating fluid to an automotive component requiring lubrication, the fluid comprising a base oil having a kinematic viscosity at between 2 and 6 cSt at 100° C., or alternatively between 2 and 5 cSt at 100° C., or in a further alternative between 2 and 4.5 cSt at 100° C., and one or more compounds of formula IV wherein x is between 160 and 190 and y is between 14 and 18, m is a positive integer of 3-6 and n is a positive integer of 20-40, and Q is hydrogen or methyl.
In still another embodiment the invention includes a method for improving the antifoam properties of a lubricating fluid while lubricating an automotive component requiring lubrication, comprising adding a lubricating fluid to an automotive component requiring lubrication, the fluid comprising a base oil having a kinematic viscosity at between 2 and 5 cSt at 100° C., and one or more compounds of formula IV wherein x is between 160 and 190 and y is between 14 and 18, m is a positive integer of 3-6 and n is a positive integer of 20-40, and Q is hydrogen or methyl and the one or more compounds of formula IV is present in an amount capable of delivering between 2 and 50 ppm of silicon to the lubricating fluid.